Q. The threshold on my back door is splitting. I’d like to repair it, or replace the entire door, frame, and threshold. I can’t afford to have it done. How hard is it to install a prehung door? What kind of door should I get, and where? The wood door has a half glass window in the top.

DEW, in Hotton’s chat room

A. You can do either or both. Cut the threshold in two pieces sideways, and pry it out. Cut any protruding nails, and buy a new threshold and nail it right in. If you cannot find a new threshold, use a pressure-treated 2 x 12, cut to the same shape as the old, and make sure you install it at the proper slant for proper runoff. Your old one split because it overhung the wood it was nailed to.

Better yet, install a prehung or setup door, which includes frame and threshold, and is insulated and weather-stripped very well. A wood door and frame is your best buy. Make the door half glass, but choose one with a Colonial type window (6 over 6) which is much stronger than a single pane of glass. Take everything out of the opening, and check the size so you can get the right size to fit snugly. The Brosco catalog shows many such setup doors, available in all lumber and big box stores.

Yes, you can do it, if you are strong and have a strong wife or friend. Those doors are heavy, especially a French double door. I have done three. You can do it.

Q. I have owned my home for 29 years and never had the chimney swept. I have a fireplace that we never use and the house is heated with oil. I’m not sure what the protocol is for having a chimney cleaned. Am I missing the boat on this or am I OK since there has never been a problem?

PAUL LUCERTO, Reading

A. Stand easy. The chimney does not need cleaning, since it has not had wood burned in it. If the house is older than the 29 years you have owned it, and wood was burned in the fireplace, you can have the chimney cleaned but the chimney sweep is unlikely to find much creosote and other byproducts of wood burning.

The only reason I could give to have the chimney cleaned, or rather inspected, is to look for any deterioration of the mortar in the chimney liner. If there is a lot of deterioration, a new stainless steel liner might be a good idea.

Q. I’d like to hang a frameless mirror on the wall. Can I simply rely on the adhesive (Liquid Nails) or must I use some J-channel or I-channel support?

GUEST, in Hotton’s chat room

A. Follow the instructions. If there are none, make sure the mirror backing can handle the Liquid Nails, and if in doubt find an adhesive that will not hurt the backing. The mirror must go on an even surface and have full contact with the wall. It might not stick well on wallpaper. Give support at the bottom of the mirror, and press on the mirror for several minutes or more till the adhesive cures. Or, buy clips that can be attached on the mirror and screwed through the flanges of those clips into the wall.

Another idea, and easier to do, is to buy a mirror with a wood frame (maybe even antique) and hang it with two super-size picture hooks with a chain. I have three, and they work well.